Lifetime of theΣ0

Abstract

A dispersion-theoretic calculation of the lifetime of the ${\Sigma }^0$ is carried out along lines suggested by previous treatments of the nucleon electromagnetic form factors. In terms of the coupling constants of the $\Sigma$, $\Lambda$, and $N$ baryons to the pion ($g_{\Lambda }, g_{\Sigma }, \mathrm{and} g$), the ${\Sigma }^0$ lifetime is predicted to be $\tau ={\left(\frac{g_{\Sigma }{g}_{\Lambda }}{g^2}\right)}^{-2\mathrm{}}\times 1.1\times {10}^{-19\mathrm{}}$ sec, irrespective of the relative ($\Lambda , \Sigma$) parity, the validity of this expression depending on the dominance of the two-pion resonating state contribution to the ${\Sigma }^0\to \Lambda +\gamma$ transition magnetic moment.